Source code for abydos.distance._consonni_todeschini_iii

# Copyright 2019-2020 by Christopher C. Little.
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Consonni & Todeschini III similarity

from math import log1p

from ._token_distance import _TokenDistance

__all__ = ['ConsonniTodeschiniIII']

[docs]class ConsonniTodeschiniIII(_TokenDistance): r"""Consonni & Todeschini III similarity. For two sets X and Y and a population N, Consonni & Todeschini III similarity :cite:`Consonni:2012` is .. math:: sim_{ConsonniTodeschiniIII}(X, Y) = \frac{log(1+|X \cap Y|)}{log(1+|N|)} In :ref:`2x2 confusion table terms <confusion_table>`, where a+b+c+d=n, this is .. math:: sim_{ConsonniTodeschiniIII} = \frac{log(1+a)}{log(1+n)} .. versionadded:: 0.4.0 """ def __init__( self, alphabet=None, tokenizer=None, intersection_type='crisp', **kwargs ): """Initialize ConsonniTodeschiniIII instance. Parameters ---------- alphabet : Counter, collection, int, or None This represents the alphabet of possible tokens. See :ref:`alphabet <alphabet>` description in :py:class:`_TokenDistance` for details. tokenizer : _Tokenizer A tokenizer instance from the :py:mod:`abydos.tokenizer` package intersection_type : str Specifies the intersection type, and set type as a result: See :ref:`intersection_type <intersection_type>` description in :py:class:`_TokenDistance` for details. **kwargs Arbitrary keyword arguments Other Parameters ---------------- qval : int The length of each q-gram. Using this parameter and tokenizer=None will cause the instance to use the QGram tokenizer with this q value. metric : _Distance A string distance measure class for use in the ``soft`` and ``fuzzy`` variants. threshold : float A threshold value, similarities above which are counted as members of the intersection for the ``fuzzy`` variant. .. versionadded:: 0.4.0 """ super(ConsonniTodeschiniIII, self).__init__( alphabet=alphabet, tokenizer=tokenizer, intersection_type=intersection_type, **kwargs )
[docs] def sim(self, src, tar): """Return the Consonni & Todeschini III similarity of two strings. Parameters ---------- src : str Source string (or QGrams/Counter objects) for comparison tar : str Target string (or QGrams/Counter objects) for comparison Returns ------- float Consonni & Todeschini III similarity Examples -------- >>> cmp = ConsonniTodeschiniIII() >>> cmp.sim('cat', 'hat') 0.1648161441769704 >>> cmp.sim('Niall', 'Neil') 0.1648161441769704 >>> cmp.sim('aluminum', 'Catalan') 0.10396755253417303 >>> cmp.sim('ATCG', 'TAGC') 0.0 .. versionadded:: 0.4.0 """ self._tokenize(src, tar) a = self._intersection_card() n = self._population_unique_card() if src == tar and n <= a: return 1.0 return log1p(a) / log1p(n)
if __name__ == '__main__': import doctest doctest.testmod()